Longitudinal Impact Force on a Special Drill for Planetary Exploration

Abstract

Special percussive mechanisms, e.g. Auto Gopher and Ultra Sonic/Sonic Driller/Corer (USDC) have been developed by NASA Jet Propulsion Laboratory and Honeybee Robotics Spacecraft Mechanisms Corporation to explore the Lunar, Martian, and other planetary subsurface and extract soil (regolith)/rock samples for further study. The percussive mechanism consists of an ultrasonic horn, a free mass (hammer) and the drill rod. This paper presents an analytical methodology to analyze the dynamic and contact analysis of the longitudinal impact of the free mass and the drill rod including the effects of structural vibration. The contact force due to impact is obtained using Hertz force-indentation relation coupled with the structural vibration obtained using mode superposition method. Numerical solution, with equilibrium iterations, of the equations of motion is implemented. The contact force was observed to follow a sinusoidal like shape, consistent with results available in literature for similar problems.